Objective Tungsten deposit formation is commonly associated with magmatic−hydrothermal fluid activities. However, during the metamorphism of W−enriched sedimentary rocks, W−rich metamorphic fluids can also develop, leading to the formation of metamorphic−type tungsten deposits. The Jiangnan Tungsten Belt, with WO₃ resources totaling 6 million tons, is the largest tungsten belt in the world. Numerous studies have indicated that the tungsten in this belt was sourced from the W−rich metamorphic basement—the Shuangqiaoshan Group. After its formation in the Neoproterozoic, this stratum underwent multiple metamorphic events, including the Caledonian, Indosinian, and Yanshanian periods. Yet, whether metamorphic tungsten mineralization occurred during these events has not been previously investigated.

Methods The Zhuxi tungsten deposit in northern Jiangxi is the largest in the Jiangnan Tungsten Belt. This study focuses on tungsten−bearing veins within the metamorphic basement (Shuangqiaoshan Group) and the surrounding metamorphic rocks. Integrated automated mineral analysis (TIMA) and in−situ microanalyses of minerals were conducted.

Results TIMA mapping identified the presence of fine−grained, disseminated scheelite within the Shuangqiaoshan Group, confirming it as a W−rich stratum. LA−ICP–MS U–Pb dating of apatite from the tungsten veins constrained their formation to the Early Cretaceous (143.7 ± 4.0 Ma). Trace element characteristics of coexisting scheelite and apatite in the veins indicate that the ore−forming fluids were derived from highly fractionated granitic magmas.

Conclusions Comprehensive analysis demonstrates that the vein−type tungsten mineralization in the W−rich metamorphic basement at Zhuxi was not formed by metamorphism, but is closely related to the widespread granitic magmatism occurring from the Late Jurassic to Early Cretaceous in the Zhuxi mining district.